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Topic: Juno Spacecraft's July 4 Jupiter Arrival: What to Expect

Syntax started this discussion 10 years ago #53,552

NASA's Juno spacecraft is scheduled to enter into orbit around Jupiter Monday night (July 4), ending its nearly five-year trek to the solar system's biggest planet.

The key event Monday is a 35-minute engine burn at 11:18 p.m. EDT (0318 GMT on Tuesday), which is designed to slow Juno down enough to be captured by Jupiter's powerful gravity.

If something goes seriously wrong with this burn, the solar-powered Juno will zoom right past the gas giant, and the science goals of the $1.1 billion mission — which include mapping the gravitational and magnetic fields of Jupiter, and characterizing its internal structure — will go unachieved.

Juno's nine science instruments were switched off last week in the lead-up to Jupiter arrival. Mission team members will begin turning them back on about 50 hours after orbital insertion, NASA officials have said.

These instruments will be calibrated and then used to study Jupiter over the next three months, but Juno won't be ready to begin its official science mission until it performs one last engine burn on Oct. 19. If all goes according to plan, this 22-minute maneuver will shift Juno into a highly elliptical, 14-day orbit around Jupiter.

The spacecraft will then observe the huge planet over the course of more than 30 orbits, gathering data that scientists hope will shed light on how, when and where in the solar system Jupiter formed.

Juno is scheduled to end its life with an intentional death dive into Jupiter's atmosphere in February 2018 — a maneuver designed to ensure that the spacecraft doesn't contaminate the potentially life-hosting Jovian moon Europa with any Earth microbes.

http://www.space.com/33333-juno-spacecraft-jupiter-arrival-timeline.html

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Anonymous B joined in and replied with this 10 years ago, 26 minutes later[^] [v] #698,159

Dr. Whom !7MHPahvoGY joined in and replied with this 10 years ago, 6 minutes later, 32 minutes after the original post[^] [v] #698,162

@previous (B)
Syntax personally oversaw all stages of the design and construction of the Juno spacecraft, and used his extensive knowledge of orbital mechanics to plan its entire journey.

Anonymous D joined in and replied with this 10 years ago, 41 minutes later, 1 hour after the original post[^] [v] #698,195

squeegee joined in and replied with this 10 years ago, 51 minutes later, 2 hours after the original post[^] [v] #698,211

Anonymous F joined in and replied with this 10 years ago, 1 hour later, 3 hours after the original post[^] [v] #698,223

adam djensen joined in and replied with this 10 years ago, 5 hours later, 8 hours after the original post[^] [v] #698,275

adam djenson replied with this 10 years ago, 38 minutes later, 9 hours after the original post[^] [v] #698,291

squeegee joined in and replied with this 10 years ago, 1 hour later, 11 hours after the original post[^] [v] #698,307

here's my knockoff Juno mission. atlas V look alike, no idea if it's even close on thrust/weight or anything like that. but it looks the part.

squeegee double-posted this 10 years ago, 1 minute later, 11 hours after the original post[^] [v] #698,308

squeegee triple-posted this 10 years ago, 42 seconds later, 11 hours after the original post[^] [v] #698,309

squeegee quadruple-posted this 10 years ago, 59 seconds later, 11 hours after the original post[^] [v] #698,310

squeegee quintuple-posted this 10 years ago, 2 minutes later, 11 hours after the original post[^] [v] #698,311

the satellite under the protective shroud. the shroud covers the whole upper stage.

squeegee sextuple-posted this 10 years ago, 7 minutes later, 11 hours after the original post[^] [v] #698,313

the main stage. i don't have any mods installed so i have no idea what this thing's max payload is or what it's thrust to weight ratio is or anything like that. i kinda just went with good proportions, one-to-three.

squeegee septuple-posted this 10 years ago, 2 minutes later, 11 hours after the original post[^] [v] #698,314

i think the best info you get in vanilla is the little engineer's report which doesn't tell you much but part count and weight. both useful, but the "engineering" stuff in this game still sucks. mods really help, i don't know why the devs don't just include Engineer.

squeegee octuple-posted this 10 years ago, 14 minutes later, 11 hours after the original post[^] [v] #698,319

i'd prefer to have launched during the day, but since i'm not doing a gravity assist i need to launch when a direct-to-kerbin-escape trajectory presents itself. for where i'm going, that means i launch when Kerbin eclipses the sun and Jool is at a favorable phase angle. if i were to do a gravity assist i would need to launch a year or two before Jool is at the correct phase angle. I'd launch to orbit the sun way, way outside of Kerbin's orbit, wait a year, then swing in fast past Kerbin on the other side of the sun and that'll sling shot me out towards Jool (if it happens to be there.)

i tried that. it does work, you spend half as much fuel, the gravity assist gives you a huge boost and you shoot out to Jool's orbit, but jool was never there when i was. it was always on the other side of it's orbit. not something i could just luck into by doing good and standard stuff. gravity assists i think are over my head. i'd need to do math, probably, and have a flight plan with launch dates/times and wacky stuff.

but, the direct route works easily enough if you aren't worried about efficiency

squeegee nonuple-posted this 10 years ago, 3 minutes later, 11 hours after the original post[^] [v] #698,320

so we launch at night and just keep going. i skip actually orbiting Kerbin and instead just launch straight into an escape trajectory and leave the Kerbin's sphere of influence. at that time i'll be orbiting the Sun, and moving in an orbit near to that of Kerbin itself.

squeegee decuple-posted this 10 years ago, 3 minutes later, 11 hours after the original post[^] [v] #698,321

the upper stage thrusting for the outer planets

after entering orbit around the sun i wait about a month and then fire up the upper stage again. this maneuver places me on a Jool intercept in, like, 4 years.

squeegee undecuple-posted this 10 years ago, 3 minutes later, 11 hours after the original post[^] [v] #698,323

you can see Jool in this picture as a small brownish dot above the fuel tank and to the right of the solar panel. it's still hundreds of millions of miles away

squeegee duodecuple-posted this 10 years ago, 2 minutes later, 11 hours after the original post[^] [v] #698,324

so it's like 30 billion km away. but we're orbiting it. but verrrry slowly. it takes another year to get to the top of the orbit (my next maneuver)

squeegee tridecuple-posted this 10 years ago, 6 minutes later, 12 hours after the original post[^] [v] #698,325

the upper stage exhausted it's fuel and the satellite is left to perform final maneuvers on it's own. (technically the entire orbital insertion burn should've been done by the satellite itself, but the second stage had extra fuel left over after boosting out here and so i didn't dump it)

this burn took about 3 and a half minutes and brings my orbit very close to Jool, i'm looping down to withing 1.7 million km well within the orbit of it's closest moon.

squeegee quattuodecuple-posted this 10 years ago, 59 seconds later, 12 hours after the original post[^] [v] #698,326

now we're talking

squeegee sexadecuple-posted this 10 years ago, 1 minute later, 12 hours after the original post[^] [v] #698,328

still highly elliptical, but after a second maneuver orbiting the planet takes a day or so instead of years.

squeegee sedecuple-posted this 10 years ago, 3 minutes later, 12 hours after the original post[^] [v] #698,329

close passes reveal detail in the clouds. that's about it. Vanilla Science instruments are shit. there's like 4 and they're all lame, and only half work in a vacuum. not even a vanilla magnetometer or telescopes. there are mods for all of that stuff though. but still.

squeegee septuadecuple-posted this 10 years ago, 3 minutes later, 12 hours after the original post[^] [v] #698,330

squeegee octadecuple-posted this 10 years ago, 34 seconds later, 12 hours after the original post[^] [v] #698,331

you can see the moon Tylo to the right of Jool

squeegee just kept on posting this 10 years ago, 3 minutes later, 12 hours after the original post[^] [v] #698,332

you can see Laythe in this picture, to the left of the satellite antennae. laythe has an atmosphere and water and i think is habitable. i'm not really sure, but i think kerbals can live on one of the Joolian moons.

squeegee just kept on posting this 10 years ago, 1 minute later, 12 hours after the original post[^] [v] #698,333

squeegee just kept on posting this 10 years ago, 37 seconds later, 12 hours after the original post[^] [v] #698,334

now it's nasa's turn

Sheila LaBoof joined in and replied with this 10 years ago, 4 hours later, 16 hours after the original post[^] [v] #698,370

adam djensen replied with this 10 years ago, 4 hours later, 21 hours after the original post[^] [v] #698,504

squeegee replied with this 10 years ago, 2 hours later, 1 day after the original post[^] [v] #698,535

squeegee double-posted this 10 years ago, 2 minutes later, 1 day after the original post[^] [v] #698,537

after making it Jool easily enough i decided to visit the moons
to do it, i built 6 micro satellites carried by a lightweight transport stage.
each satellite is a probe core, gyros, an antenna and i skipped sensors since they're lame

squeegee triple-posted this 10 years ago, 4 minutes later, 1 day after the original post[^] [v] #698,539

it's pretty simple, park it in a big eccentric orbit around Jool, then release each probe individually and maneuver them to intercept different moons. each micro-sat carries enough fuel (and are light enough) to get into orbit around the moons.

squeegee quadruple-posted this 10 years ago, 46 seconds later, 1 day after the original post[^] [v] #698,540

transferring fuel

squeegee quintuple-posted this 10 years ago, 41 seconds later, 1 day after the original post[^] [v] #698,541

releasing micro-sat

squeegee sextuple-posted this 10 years ago, 7 minutes later, 1 day after the original post[^] [v] #698,543

getting ready to thrust for Laythe intercept. everything was going according to plan. i got the laythe intercept plotted, did the maneuver, but started having electrical problems before i could do the insertion burn. the solar cells were working at very low efficiency and weren't able to overcome powerdrain. the micro-sat ended up flying past laythe, completely dead, and then settled into orbit a useless orbit around Jool.

i tried two more times, and tried powering systems down for the trip, but when i got to Tylo with the next satellite i wasn't able to power back up (i turned off the backup battery). i didn't really have any options, the micro sats were just built without enough electrical generation. the mission was a huge disaster, and a great stain on the Space program.

squeegee septuple-posted this 10 years ago, 1 minute later, 1 day after the original post[^] [v] #698,544

very costly, too, using a super-heavy lift variant of the Atlas V. it was like launching 2 juno satellites at the same time

Sheila LaBoof replied with this 10 years ago, 4 hours later, 1 day after the original post[^] [v] #698,567

squeegee replied with this 10 years ago, 7 hours later, 1 day after the original post[^] [v] #698,670

@previous (Sheila LaBoof)
yeah! i'm trying to find specifics like orbital altitude and stuff but i haven't yet.
here's a GIF showing the flight plan and how complex a gravity assist is. the timing has to be flawless

squeegee double-posted this 10 years ago, 10 minutes later, 1 day after the original post[^] [v] #698,675

kook !!OPZbEQMT1 joined in and replied with this 10 years ago, 3 hours later, 1 day after the original post[^] [v] #698,703

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